Prevalence and seasonal transmission of Schistosoma haematobium infection among school-aged children in Kaedi town, southern Mauritania

Abstract

BackgroundMauritania is at the fringe of transmission of human schistosomiasis, which mainly occurs in the southern and southeastern parts of the country. This study aimed to assess the influence of rainfall seasonality on the prevalence of Schistosoma haematobium infection among school-aged children in Kaedi, southern Mauritania.MethodsCross-sectional surveys (i.e. parasitological, malacological and observations on water-related human activities) were carried out in Kaedi between September 2014 and May 2015, during both the wet and dry seasons. A total of 2162 children aged 5–15 years provided a single urine sample that was subjected to S. haematobium diagnosis. Snails were sampled and checked for cercarial shedding. Water contact patterns of the local population were recorded by direct observation.ResultsThe prevalence of S. haematobium was 4.0% (86/2162, 95% confidence interval (CI): 3.2–4.9%) with a geometric mean egg count per 10 ml of urine of 3.7 (95% CI: 2.8–4.3). Being male (adjusted odds ratio (aOR) 1.78, 95% CI: 1.13–2.80), being at primary school (aOR 1.73, 95% CI: 1.04–2.87) and dry season (aOR 0.56, 95% CI: 0.35–0.89) were significantly associated with S. haematobium. Among 284 potential intermediate host snail specimens collected over the rainy and dry seasons, three species were identified: Bulinus senegalensis (n = 13) and B. forskalii (n = 161) in the rainy season, and B. truncatus (n = 157) in the wet season. No snail was shedding cercariae. On average, seven human water contacts were recorded per hour per observer over a 28-day observation period. Twelve types of water contact activities were identified among which, swimming/bathing was predominant (n = 3788, 36.9%), followed by washing clothes (n = 2016, 19.7%) and washing dishes (n = 1322, 12.9%). Females (n = 5270, 51.4%) were slightly more in contact with water than males (n = 4983, 48.6%). The average time spent in the water per person per day was 14.2 min (95% CI: 13.8–14.6 min). The frequency and duration of water contact followed a seasonal pattern.ConclusionOur findings demonstrate a low prevalence and intensity of S. haematobium among school-aged children in Kaedi. Appropriate integrated control measures, including health education among at-risk communities and snail control may help to interrupt transmission of S. haematobium in Kaedi.

Prevalence of schistosomiasis and associated risk factors among school children in Um-Asher Area, Khartoum, Sudan

“…Thirty-one African countries including Sudan have the great burden of this disease, and millions of individuals have been suffering from schistosomiasis [ 3 ]. Africa houses at least 90% of infected people requiring schistosomiasis treatment [ 5 ].…”

Seasonal Pattern and Occurrence of Schistosoma haematobium Egg Excretion among Pregnant Women in Munyenge, South West Region, Cameroon

“…This corroborates findings of Houmsou [21] in Nigeria, who reported no monthly or seasonal difference in the prevalence of infection. On the contrary, well-marked seasonal variation in Schistosoma infection was reported by several authors [16,17,[54][55][56]. The absence of seasonal difference in the occurrence in infection may suggest perennial transmission of infection noting high dependency of the population on stream water source.…”

“…Satellite temperature and precipitation products are suitable in providing useful information to understand and model the relationship between meteorological conditions and Schistosoma prevalence [9]. In recent years, a number of studies have indicated that S. haematobium infection exhibits seasonal variation [15][16][17] and that infection may vary between countries and even between regions in the same country. In some areas, the prevalence of S. haematobium is higher in the dry season [17][18][19], while in other areas, it is higher during the rainy season [20,21].…”

Comparative analysis of time-based and quadrat sampling in seasonal population dynamics of intermediate hosts of human schistosomes

“…Indeed B. pfeifferi has been shown to prefer solid supports (such as wood and leaves) and bedrock to sand and gravel [41]. Moreover there are accounts of the preference of the intermediate hosts for plastic waste [63], although no quantification of this preference exists to our knowledge. In this perspective a limitation of this study was to not have done specific trials to determine the degree of randomness obtained using our procedure for the random positioning of sampling quadrats, in particular the effect of the repositioning of the quadrat if it didn't land within the predefined distance to the shoreline with respect to the snail species' substratum preferences.…”